Each business day, TheStreet.com Ratings compiles a list of the top five stocks in five categories -- fast-growth, all-around value, large-cap, mid-cap and small-cap -- and publishes these lists in the Ratings section of our Web site.

This list is based on data from the close of the previous trading session. Today we focus on mid-caps. These are stocks of companies that have market capitalizations of between $500 million and $10 billion that rank near the top of all stocks rated by our proprietary quantitative model, which looks at more than 60 factors.

The stocks must also be followed by at least one financial analyst who posts estimates on the Institutional Brokers' Estimate System. They are ordered by their potential to appreciate.

Note that no provision is made for off-balance-sheet assets such as unrealized appreciation/depreciation of investments, market value of real estate or contingent liabilities that might affect book value. This could be material for some companies with large underfunded pension plans.

Gorman-Rupp ( GRC) designs, manufactures and sells pumps and related equipment for use in various liquid-handling applications, such as wells, wastewater, agricultural systems, fire protection and military uses. The company's pumps have a variety of uses, from pumping refined petroleum products for fueling aircraft and water for fire fighting to ice cube-dispensing equipment and office-copy machines.

Our buy rating on Gorman-Rupp has not changed since November 2005. The company's strengths can be seen in multiple areas, such as its revenue and net income growth, largely solid financial position, and impressive record of earnings per share growth.

Revenue for the first quarter of fiscal 2008 rose 9.4% year-over-year. The company's first-quarter net income of $7.15 million represents a 40.5% increase from the $5.09 million reported one year ago. As a result, the company was able to report record EPS of 43 cents a share, representing an improvement of 41.4% from 30 cents a year ago. This adds to the company's trend of positive EPS growth over the past two years. Finally, with no debt to speak of, Gorman-Rupp has a debt-to-equity ratio of zero.

Management was pleased with what it considers to be a very good start to a year in which Gorman-Rupp will celebrate its 75th anniversary. The company reported that it will continue to grow in the areas of water and wastewater handling and infrastructure renewals and expansion. Consolidation and expansion of the company's Mansfield, Ohio, facilities is expected to result in increased efficiency and capacity in the future. Bear in mind, however, that the machinery industry as a whole faces challenges from rising commodity costs. Customers have historically absorbed the commodity increases as surcharges that have helped cover the difference, but there is no guarantee that this will continue.

American Ecology ( ECOL) is one of the nation's oldest providers of radioactive, hazardous and industrial waste management services. The company's customers are commercial and government entities, such as nuclear power plants, medical and academic institutions, steel mills, refineries and chemical production facilities. A significant portion of the company's revenue from operating disposal facilities -- those that actively receive and treat waste materials -- comes from discrete, one-time clean-up projects, which may span weeks, months or years depending on project scope.

American Ecology's Non-Operating Disposal Facilities segment consists of facilities that no longer receive waste materials but continue to be monitored and maintained as part of the treatment of previously received waste materials. Other services include waste stabilization, encapsulation and chemical oxidation.

We have rated American Ecology a buy since October 2005. Strengths such as revenue growth, a largely solid financial position, and a notable return on equity influenced this rating. For the first quarter of fiscal 2008, American Ecology's revenue rose by 18.6% year-over-year. This growth appears to have trickled down to the bottom line, improving EPS by 18.5% over the first quarter of 2007. In fact, the company has demonstrated a pattern of positive EPS growth over the past two years. A slight improvement in return on equity can be seen as a modest strength for the company. Finally, while total debt increased slightly year-over-year, it remains at an almost negligible level.

Badger Meter ( BMI) manufactures and markets flow measurement and control products. These products measure a variety of liquids, such as water, oil and lubricants. The company serves utilities, municipalities and industrial customers worldwide. Badger operates in two business segments, Utility and Industrial.

The utility products are used by both public and private water systems, while the industrial products provide flow measurement solutions in a variety of specialty industries including petroleum, food and beverage, pharmaceutical, and concrete. The company was founded in 1905, and has major U.S. facilities in Wisconsin and Oklahoma. Foreign facilities are located in Mexico, Germany and the Czech Republic.

Badger has been rated a buy since August 2003. The company's strengths include its revenue growth, net income growth and return on equity. For the first quarter of 2008, Badger's revenue rose by 29.9% year-over-year. This growth appears to have helped boost earnings per share, which improved significantly in the first quarter, rising from 17 cents in the first quarter of 2007 to 41 cents. Net income increased by 134.1% over the same period, rising from $2.57 million to $6.02 million. Finally, return on equity has improved slightly from 18.62% to 22.34%.

Powered by its strong earnings growth of 141.17% and other important driving factors, this stock has surged by 51.56% over the past year. While this makes the stock somewhat expensive compared to the rest of its industry, we felt that the company's strengths justify the higher price levels at this time.

Bear in mind, however, that Badger's future performance could be affected by any regulatory changes, especially those dealing with the use of lead, which is used in the manufacture of certain meters, or the use or licensing of radio frequencies necessary for the company's automatic meter reading and advanced metering infrastructure products. Badger's future results could also be affected by the overall health of the U.S. economy, including housing starts and overall industrial activity, and any changes in foreign economic conditions, including currency exchange rates.

Ameron International ( AMN) manufactures highly engineered products and materials for the chemical, industrial, energy, transportation and infrastructure markets worldwide. The company's products include such items as high-performance coatings and surfacer systems for the preservation of structures, molded fiberglass pipes and fittings, ready-mix concrete, and products and services used in the construction of water pipelines. Products are produced at plants in a variety of locations throughout the U.S. and through subsidiaries abroad.

Ameron has been rated a buy since June 2005. Strong performances from the Fiberglass-Composite-Pipe Group and TAMCO (Ameron's 50%-owned steel mini-mill) led to higher results in the second quarter of fiscal 2008. The company reported a slight revenue increase of 1.9% year-over-year, which appears to have helped boost EPS from $1.63 in the second quarter of fiscal 2007 to $1.78 in the most recent quarter. Net income increased 3.4% when compared to the same quarter one year prior, rising from $15.80 million to $16.33 million. Return on equity also improved slightly, and the company appears to be successfully managing its debt levels.

Management was overall pleased with the year-to-date results, as the company's performance for the first half of fiscal 2008 was positive. The company anticipates steady returns for the year from its various businesses, with TAMCO and the Fiberglass-Composite-Pipe Group expected to continue performing at record levels.

However, weak market conditions will most likely continue to negatively affect the Infrastructure Products Group. Bear in mind that the Building Products industry's performance is cyclical, depending on the overall health of the U.S. economy. The state of the housing and auto markets in particular could impact this industry and, therefore, this stock.

Ametek ( AME) manufactures electronic instruments and electromechanical devices. The company has operations throughout the United States and in more than 30 other countries. The company's Electronic Instruments segment manufactures advanced monitoring, testing, calibrating and display instruments for the process, aerospace, power and industrial markets worldwide. The Electromechanical segment produces highly engineered electromechanical connectors for hermetic (moisture-proof) applications, specialty metals for niche markets, and brushless air-moving motors, blowers and heat exchangers. The products are used in floor care and other specialty applications.

Ametek has been rated a buy since November 2002. The company's strengths include its consistent revenue, EPS and net income growth, as well as its solid stock performance. In addition, Ametek's minimal exposure to the housing and automobile markets could insulate it from the sluggish U.S. economy. For the first quarter of 2008, the company reported a 30.4% increase year-over-year in earnings, led by operational improvements and a strong revenue growth of 21.0%. Continuing its pattern of EPS growth over the past two years, the company again reported improved EPS from 48 cents in the first quarter of 2007 to 62 cents in the most recent quarter. Net income grew to $66.36 million from $50.90 a year ago. Furthermore, operating cash flow increased 39.0% to $77 million. Additionally, the company recently paid a quarterly dividend of 6 cents on March 31, 2008.

On June 12, the company announced its plans to acquire Vision Research, a privately held manufacturer of high-speed digital imaging systems used for motion capture and analysis in numerous test and measurement applications. Vision Research, located in Wayne, New Jersey, has estimated annual sales of approximately $37 million, and will become part of AME's Electronic Instruments Group -- a provider of advanced monitoring, testing, calibrating and display instruments for the process, aerospace, power and industrial markets worldwide.

Going forward, Ametek estimates revenue for the full year 2008 to increase in the high teens on a percentage basis, while earnings are estimated to be in the range of $2.47 to $2.52 a share. Management also expects earnings for the second quarter to be approximately 61 cents to 63 cents, an increase of 13% to 17% over last year's second quarter results. However, these results could be negatively affected should the company fail to successfully integrate its recent acquisitions. Other risks include the price and availability of raw materials and changes in the competitive environment.

Our quantitative rating is based on a variety of historical fundamental and pricing data and represents our opinion of a stock's risk-adjusted performance relative to other stocks.

However, the rating does not incorporate all of the factors that can alter a stock's performance. For example, it doesn't always factor in recent corporate or industry events that could impact the stock price, nor does it include recent technology developments and competitive dynamics that may affect the company.

This article was written by a staff member of TheStreet.com Ratings.

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